Projectors are widely used in many circumstances. Recently, with increasing development of science and technology, a pico projector (also referred as a microdisplay) has been introduced into the market. The pico projector is designed to have small size and light weightiness. Generally, the pico projector is embedded into a portable electronic device (e.g. a mobile phone or a personal digital assistant), so that the pico projector may be directly utilized. Alternatively, the pico projector is separated from the portable electronic device, and thus the pico projector may be operated after the pico projector is in communication with the portable electronic device. By mean of the pico projector, a corresponding projection image may be projected on a flat projection surface to be viewed by the user. In such way, the image to be shown may be projected in a maneuverable and real-time manner.
Generally, the pico projector uses light sources to emit light beams, and projects the light beams on the projection surface through a projection module. In a conventional pico projector, the projection module is for example an LCoS (liquid crystal on silicon) panel, a reflective LCD (liquid crystal display) panel, a DMD (digital Micro-mirror device) or a micro scanning mirror (i.e. according to a MEMS technology). Before the light beams are projected out through the projection module, the light beams are homogenized, focused or shaped by associated optical elements of the pico projector. After the light beams are homogenized, focused or shaped, the adjusted light beams are projected out. Generally, the light sources used in the pico projector are for example LED light sources or laser light sources.
FIG. 1 is a schematic planar view illustrating a portion of a conventional pico projector. As shown in FIG. 1, the conventional pico projector 1 comprises three primary color light sources 11, 12 and 13. For example, the color light source 11 is a red light source, the color light source 12 is a green light source, and the color light source 13 is a blue light source. The three primary color light sources 11, 12 and 13 are laser light sources. The pico projector 1 further comprises three collimator lenses 110, 120 and 130 corresponding to the three primary color light sources 11, 12 and 13, respectively. The color light beams from the three primary color light sources 11, 12 and 13 are adjusted by the collimator lenses 110, 120 and 130. The pico projector 1 further comprises two dichroic mirrors 141 and 142. The color light beams from the three primary color light sources 11, 12 and 13 are selectively transmitted through or reflected by the dichroic mirrors 141 and 142, so that the three color light beams are mixed with each other. Afterwards, the mixed light beam is projected as a projection image by a projection module 15.
The conventional pico projector 1 further comprises a fixing module 10 for fixing and installing the light sources, the collimator lenses, the dichroic mirrors or other optical elements. However, the conventional pico projector still has some drawbacks. For example, in the fixing module 10, specified spaces should be retained at the positions near the collimator lenses 110, 120 and 130 for allowing associated jig tools to clamp, install or adjust the collimator lenses 110, 120 and 130. Under this circumstance, the overall size of the pico projector fails to meet the miniaturization requirements.